B off-lattice displacement in B-doped Si was observed under Si self-interstitials (I s) supersaturation induced by ion irradiation at room temperature. B lattice location has a characteristic channeling mark and was studied by nuclear reaction analyses and ion channeling technique, through the comparison of the performed angular scans along the⟨ 100⟩ and⟨ 110⟩ crystal axes and the simulated scans by FLUX code. Solid and liquid-phase epitaxies and molecular beam epitaxy were used to prepare B-doped Si samples in order to investigate samples with B concentration in the range between 10 19 and 10 21 at/cm 3. B off-lattice displacement is limited by the fluence of excess I s per B atom. Small B-I s clusters (BICs) were formed as consequence of the interaction with I s produced during the ion irradiation. Clusters structures were investigated by simulating the channeling angular scans of cluster configurations …